The Tabernas Basin in southeast Spain is a Neogene intermontane basin which filled with sub‐aerial and submarine fan conglomerates grading into turbidite sandstones towards the basin centre. The basin history involved the development of Seravallian‐Tortonian subaerial fans which coalesced southwards from the basin margin. Increasing water depth in the Tortonian led to a submarine development of these fans. The coarse fan conglomerates are colonized almost solely by barnacles of the species Megabalanus tintinnabulum, known from Miocene‐Recent deposits. The barnacles occur in seven preservational‐state assemblages, which provide a record of the colonization of stabilized mass‐flow conglomerates and of subsequent reworking episodes. M. tintinnabulum is known from intertidal environments today. In situ clusters developed on the fan conglomerates record the transition of the fans from subaerial to submarine environments. Mass‐flow deposits rich in barnacle shell debris are representative of basin‐wards reworking of intertidal clusters and illustrate relative increase in water depth. A further shallowing episode is identifiable by the recolonization of mass flows by in situ barnacle clusters. This case history is demonstrative of the utility of some barnacles in determining basin history with respect to minor sea level fluctuations.

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Mountkeithite [(Mg,Ni)9(Fe3+,Cr,Al)3(OH)24]3+[(CO{in3,SO4)1.5(Mg,Ni)2(SO4)2(H2O)11]3− occurs with pyrite, magnetite, magnesite, hexahydrite, and morenosite in a low-temperature hydrothermal vein system in the Mount Keith disseminated nickel sulphide deposit, Western Australia. Electron-microprobe analyses gave the following average composition: MgO 31.7, NiO 6.1, CuO 0.1, Cr2O3 6.1, Fe2O3 8.3, Al2O3 2.6, SO3 14.7; microanalysis for C and H gave CO2 3.9, H2O 30.6; total 104.1. The X-ray powder diffraction pattern has the following strongest lines: 11.30(10), 5.63(8), 4.63(2), 3.765(6), 2.645(4), 2.545(4), 1.554(5), and 1.505(3); these can be indexed on a hexagonal cell with a = 10.698 Å, c = 22.545 Å.Mountkeithite occurs as friable aggregates and rosettes composed of soft, pearly to translucent, pale pink to white flakes with perfect basal cleavage. Optical properties are uniaxial negative with ɛ = 1.51 and ω = 1.52; weakly dichroic from colourless to palest pink. Specific gravity is 2.12 (calc. 1.95). Mountkeithite is soluble, with efferves-cence, in dilute HCl. Mountkeithite changes to a pyroaurite-like phase, with a 7.8.Å basal spacing when immersed in water, but can be changed back to an 11.3 Å phase by immersion in 1M MgSO4; mountkeithite also collapses to a 7.8 Å basal spacing under vacuum. Phases similar to mountkeithite have been synthesized by immersing grains of stichtite in 1M MgSO4, at 20, 50, 105, and 200°C.The structure of mountkeithite is interpreted as consisting of positively charged brucite-like hydroxyl layers, containing both divalent and trivalent cations, separated by about 7 Å-thick, negatively charged interlayers containing carbonate and sulphate anions, magnesium sulphate, and water. Carrboydite, motukoreaite, and hydrohonessite are minerals with similarly large basal spacings of 10–11 Å, and are also believed to have pyroaurite-related structures with expanded interlayers.

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A special feature of the composite Coastal Batholith of Peru is the presence of ring complexes, which suggests a very high-level crustal environment and a direct connection between the magmas of the constituent plutons and caldera-centred volcanicity. The nature of four such complexes is commented on in detail, especially the high degree of structural control of emplacement, the association of mylonites and tuffisites with ring-fractures, the roles of stoping, fluidization and entrainment during the intrusion of ring-dykes, the co-existence of highly mobile magmas, their pulsatory injection, and the connection between these and volcanics of the same general age. Such mechanisms of cauldron subsidence located at the plutonic-volcanic interface operated throughout much of the 70 m.y. history of the batholith.Un caractere particulier du batholite compose de la c6te du Perou est la presence de complexes circulaires ce qui suggere un ambient localise tres haut dans la croCite et une connexion directe entre les magmas des plutons constituents et le volcanisme du type caldeira. La nature de quatre de tels complexes est commente en detail, particulierement le haut degre d'influence structurale sur la mise en place, I'association de mylonites et tufisites avec les failles circulaires, les r6les du stoping et de la fluidisation oh les fragments des roches ont e t t entraines dans le mouvement d'un gaz pendant I'intrusion des dykes circulaires; la coexistence des magmas tres mobiles, leur injection pulsatoire, et la connexion entre ceux-ci et les produits volcaniques d'ige semblable. De tels mecanismes d'affaissement de cauldron, localises a I'interphase entre les niveaux plutoniques et volcaniques, ont opere pendant une grande partie de I'histoire de 70 millions d'annees du batholite.

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